Metallurgical process.



- w. E. GREENAWALT;

METALLURGICAL PROCESS.

. APPLICATION FILED NOV. 23, l9l 2- RENEWED JAN. 17, 19!]. 1,218,177Patented Mar. 6,1917.

WITNESSES:

srnrns ca rn METALLURGICAL rnoonss.

Application filed November 23, 1912, Serial No. 733,201. Renewed January17, 19H

To alleohom it may concern:

Be it known that I, WILLIAM E. GREENA- wxL'r, a citizen of the UnitedStates, residing in the city and county of Denver and the State ofColorado, have invented certain new and useful Improvements inMetallurgical Processes, of which the following is a specification. I

My invention relates to improvements in metallurgical processes and hasfor its more immediate object the cheap recover of copper from its oresWith a simultaneous recovery of the sulfur combined With-the copper whenprecipitated as the sulfid, although it is not intended to limit it tothis use alone.

Hydrogen sulfid makes an excellent precipitate of copper from itssolutions, for, not only is the copper precipitated, but an equivalentof acid is regenerated, and this regenerated acid solution may again beapplied to the ore and thus the process may be made cyclic and the costof extraction materially reducedf The principal difliculties in the useof hydrogen sulfid have been the cost of producing it, and theconversion of the sulfid pre cipitate into metallic copper. It ispurposed in this process to convert. the copper into metal and recoverthe elementalsulfur or convert it direct into hydrogen sulfid forfurther precipitation, and thus make the precipitation of copper withhydrogen sulfid commercially applicable.

If copper sulfid is heated in anoxidizing atmosphere, as in a roastingor smelting furnace, or converted into blister copper by a bessemerizingprocess, the combined sulfur is eliminated as sulfur dioxid. If, on thecontrary, it is heated in a reducing atmosphere and the temperature israised sufli ciently high, the copper 'sulfid is dissociated and thesulfur volatilized in its elemental form, and this sulfur, undersuitable conditions, may be directly converted into hydrogen sulfid. Adifiiculty occurs, however, in heating the copper sulfid in a reducingatmosphere and get the conditions best adapted to the reactions. I havefound that this can be done, under almost ideal conditions, by'chargingthe copper sulfid into an electric furnace, where all the conditions canbe maintained to get the best results both for the recovery of thecopper and Specification of Letters Patent.

the generation of hydrogen sulfid or the recovery of the sulfur.

In charging the copper sulfid into the furnace and subjecting it to atemperature sufliciently high to dissociate the copper sulfid andvolatilize the sulfur, it is preferably charged in a fused state,.s1ncethe voluminous precipitate of copper sulfid is more readily chargedafter having been fused or during fusion. The copper sulfid, however,can be charged direct into the electric furnace and fused there eitherby the current, or otherwise before applying a temperature suflicientlyhigh to dissociate it.

' It is desirable to mix with the copper sulfid a certain amount of coalor other reducing agent, in addition to'covering the charge With coal orcoke. The idea being to maintain a reducing atmosphere and unnecessarilyprevent the sulfur from being oxidized to sulfur dioxid. Other sulfidsmight answer the same purpose very well, but copper sulfid is the onemore directly concerned in this process, and the application of othersulfids will be readily understood.

A completedescription of the process, in its application to extractingand precipitating copper from itsores, its precipitation from thesolution with hydrogen sulfid, and the method of treating the sulfidprecipitate to recover the copper and volatilize the sulfur which maythen be converted into hydrogen sulfid, is best described by referringto From to'wer 2 the cuprous chlorid solution, now contalning also anequivalent of free regenerated acld, flows into storage and regulatingtank 4, and from there it is drawn in a continuous stream into theprecipitating tower 5, where the copper is precipitated with hydrogensulfid, preferably obtained from the apparatus 18. The reaction is:

I thus regenerating an additional equivalent of acid. Gold and silver,if present, are simi .larly precipitated. Ifan alkaline or sulfatesolution is used to dissolve the copper, the application of sulfurdioxid in reducing tower 2 will usually be omitted, and the solutionflowed-directly from the leaching vat 1 to the precipitator 5.@rdinarily, however, the chlorid solution is to be preferred, for thereason that the gold and silver may be extracted with the copper, andthe regeneration of the extra acid with sulfur dioxid, will materiallycheapen the process.

From the precipitating'tower 5, the precipitated solution now containingthe precipitate in'suspen sion, flows into settling tank 7, where thesulfid precipitate settles to the bottom and accumulates until its re-'moval is desirable; If the supernatant and regenerated acid solution isfree from suspended matter, as will be the case ifsufiicient time isallowed for it to settle, it may be pumped by means of pump 12 eitherdirectly back to the leaching vat or into the storage tank 15. It willusually be found better to filter the precipitate and regeneratedsolution, as through a filter press 10, when all suspended matter willbe caught in the press, and the clear solution flowing into;

. tank 11 may be pumped to tank 15 by means of the pump 12 and pipe linelat.

llhe regenerated solution in tank 15 will contain all its salts at theirlowest valencies, and possibly also some hydrogen sulfid. In

" this condition it is not advisable to apply it to the ore, especiallyif any chemical reaction is desired from the salts in the solution withthe copper in the ore. In order to make the solution most effective itis oxidized, or the valencies of the salts raised by applying air,chlorin, or other oxidizing agents to the solution in the oxidizingtower 16. If there is arem? second analytical groups, so that theprecipi tate will always be reasonably pure no matter how impure thesolution may be. If an alkaline solution is used, detrimental impuritieswill not be dissolved.

lhe precipitate accumulates in tank '3' until it is desirable to removeit. The acid is then drained as completely as possible, and

the-precipitate. washed and filtered. It is then treated, preferably, asfollows, largely with. a viewof re-using' the sulfur either for theproduction of hydrogen sulfid or sulfur dioxid and to get the copperiniits metallic condition.

The precipitate after being washed and filtered, and preferably fused esin 'a reverberatory furnace to make' it more compact,

is then charged, either solid or molten, into the electric-furnace 18,where it can be heated to the desired temperature in a reducingatmosphere. The fine and voluminous precipitate might be charged directinto the electric furnace and good results obtained. in any case, areducing agent, such as coal or coke, is charged with the copper sulfidd may be covered with a layer of coke as.

28' represents the positive, and 2a negative electrode of the electricfurnace 1-9 represents the bottom portion of the furnace and 20 aremovable top for chargin the copper sulfid and for ladling out moltencopper. The bottom may contain perforations, as in an ordinary copperconverter, through which reducing gases may be forced into the charge,if desired. W

the current is turned on the charge is heats as desired. This may bedone in a reducing atmosphere and without the necessity of in troducingundesirable gases into the interior of the furnace, as in ordinarysmelting operations. V7 hen the temperature is sufiiciently high, say ata white heat, the copper suliid is dissociated, probably by electrolyticaction, and sulfur volatilized. V/hile the sulfur is being volatilized,steam, and pref erably reducing gases are introduced into 1 highlyheated furnace, through the steam pipe 25 and the gas pipe 26, whichcombines with the sulfur to form hydrogen suhid.

Some hydrogen and other reducing gases may also be produced at the sametime. The gas is exhausted from the furnace through pipe 30 by means ofthe exhauster 6, and forced into tower 5, to precipitate the copper fromits solution. 'The coal or coke, charged with the copper sulfid, willtend to form reducing gases in the furnace, so that the introduction ofsteam alone at times may be quite suiiicient. The steam introducedthrough pipe 25 may act as an injector to introduce the reducing gasesfrom pipe an ii and both may be regulated asdesired.

- as silica, to slag it.

If it is intended to make the process'indirect, the sulfur may bevolatilized and recovered as flowers of sulfur, and the sulfur sorecovered may then be used as desired. 10

l/Vhile the method of fusing the sulfid, be fore charging into thefurnace, is preferred, it is quite feasible to charge the precipitatedirect, either alone, or mixed with some reducing agent such as coal orcoke. The electric current can then be used to bring it to incandescenceand fusion, after which suflicient heat may be applied to dissociate thecopper sulfid.

A decided advantage in treating the copper sulfid in this way instead ofblowing it to blister copperv by the converter process, is, that thesulfur may be recovered in useful form. The advantage of using theelectric current to bring the sulfid to the high temperature necessaryto effect dissociation, is, that this can readily be done in a reducingatmosphere, and thus the desired results may be better obtained.

The treatment of the sulfid precipitate, which is practically purecopper sulfid, differs from smelting, either with fuel or by means ofthe electric current, in that no flux is required and the copper sulfidmay be dissociated by the electric current by heat alone, lea vingpractically .pure copper. If a matte or copper sulfid ore is smelted torecover the metallic copper, air is required to oxidize the iron, and aflux, such By simply dissociating the copper sulfid the metal is readilyrecovered and the sulfur is conveniently converted into a precipitant,and, in addition'to precipitating more copper the precipitant rendersits equivalent inacid for further solution of copper.

The volatilized sulfur may be used either as sulfur dioxid or hydrogensulfid if used as hydrogen sulfid it is perferably at once convertedinto the precipitant in the electric furnace. If used as sulfur'dioxidit is preferably burned in the burner 3, and the gas conducted to tower2.

m Any volatile copper, such for example as the chlorid, from theelectric furnace, is conducted with the precipitant into tower 5, andthere recovered as the sulfid.

If the resulting metallic" copper does not :contain any preciousmetalsworth recovering, it may at once be converted into a commercialbrand of the metal; if it contains precious metals worth recovering, itmay be electrolyzed in the ordinary way. I

The application of sulfur dioxid to reduce the copper to the cuprouscondition is a preferred arrangement; the hydrogen sulfid may be applieddirect to the cupric chlorid solution, only more hydrogen sulfid will berequired and less acid will be regenerated.

If it is necessary the ore is given, preferably, a chloridizing roast,and then leached with water or regenerated acid solution, the resulting,cupric chlorid solution treated with sulfur'dioxid and hydrogen sulfid,as described for oxidized ore, and the precipitated and regenerated acidsolution returned to the ore to dissolve the copper not soluble inwater. The same or similar result is obtained if the ore is given asulfatizing or oxidizing roast. Whether the roast be oxidizing orsulfatizing, or chloridizing, the copper may be precipitated direct withhydrogen sulfid without the previous application of sulfur dioxid.

It is evident that by the cyclic use of the solvent, it will ultimatelybecome charged with chlorids or sulfates, or both. The chlorids andsulfates form an effective combination to make the copper soluble ifapplied to the rawore before roasting, consequently, when the solutionbecomes charged with soluble matter, the raw oreis saturated with it,and roasted. The chlorids acting with the sulfates, convert the copperinto soluble chlorid or sulfate while the impurities themselves, such asiron chlorid or sulfate, become insoluble, as the oxid. In this way agiven amount of salt or 'chlorin may be used cyclically and indefihaveto be given a preliminary roast, the

process offers a cheap and effective .way of making the copper soluble.The soluble copper may then be precipitated and acid regenerated and theregenerated acid solution used' to dissolve the copper as'in oxidizedores. Vhen the solution becomes charged with soluble matter it isapplied to the raw ore, and the ore roasted, to make as much of thecopper soluble in water as possible. The regenerated acid is also highlyeffective in making the copper soluble by roasting the ore with thesoluble salts.

. The solution charged with soluble matter may be evaporated and thesalts mixed with the ore before roasting, but this may be considered asthe equivalent of the application of the solution direct to the raw ore,since the Water is evaporatedfrom the ore before roasting can proceed.

I claim: '1. metallurgical process Which consists in fusing a sulfidprecipitate, and then at i an elevated temperature applying an electriccurrent to separate-the sulfur from the metal,'and applying steam andreducing gases to the highly heatedliberated sulfur to form hydrogensulf 2. A metallurgical process Which ccnsists in fusing copper sulfid,and then at an elevated temperature applying an electric current toseparate the sulfur, from the metal; and applying steam in zi'reducingatmosphere to the highly heated sulfur to form hydrogen sulfid.

W'ILLIAME. GREENAVVALT. Witnesses:

F RED L. SCOTT, 'ssm G. SELLERS.

